1. Field of the Invention
This invention generally relates to a friction member. More specifically, the present invention relates to a friction member used in a clutch device of an automobile or the like.
2. Background Information
A dry clutch device of an automobile is provided with a friction facing, which is pressed against a flywheel for frictionally transmitting power.
The friction facing for a dry clutch device is produced in the following manner. First, glass yarn made of, e.g., only glass fibers or a mixture of glass fibers and metal lines twisted together is prepared. Then, the glass yarn is moved into an impregnation tank containing a composition of rubber, curing agent, thermosetting resin and other materials dissolved in a solvent. Thus, the glass yarn is impregnated and coated with the above composition. The yarn for the friction member thus prepared is wound and preshaped into an annular form (i.e., a product form). Thereafter, the final product of the friction facing is completed through thermal pressing, curing, polishing and other steps.
In the manufacturing method of the friction facing described above, the glass yarn is immersed in the impregnation tank. The glass yarn is impregnated and coated with the composition. Therefore, the resin composition moves into the glass yarn.
It has been known that when starting a vehicle, automobile clutch judder is affected by the amount of spaces which are present within the facing. To suppress the judder, it is necessary to increase the porosity by increasing a ratio of spaces within the molded portion. However, it is difficult to increase the porosity of the yarn in conventional methods of facing manufacture because the resin is present within the glass yarn.
In the prior art, therefore, the porosity of the molded portion is controlled by controlling the pressure during the thermal molding. However, although the judder can be suppressed, an increase in porosity of the molded portion lowers the resistance against wearing, and thus shortens the life of the facing.
In view of the above, there exists a need for a friction member which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.